How I can get all data from a table in Mysql DB with Java

Question

How can I get all data in Mysql DB with JAVA

I Have this code but he get only first row

if (connection != null) {
System.out.println("You made it, take control your database now!");
        Statement st = connection.createStatement();
        String sql = ("SELECT * FROM nc;");
        ResultSet rs = st.executeQuery(sql);

        if(rs.next()) {
        int id = rs.getInt("id");
        String str1 = rs.getString("Name");
        String str2 = rs.getString("City");
System.out.format("%s, %s, %s\n", id, str1, str2);

and i get in the screen : id 0 , Name Nizar, City Casablanca

so how ican get all rows in my database and thank you

use while(rs.next())

andreih
– andreih

2013-06-05 08:16:26 +00:00
Commented Jun 5, 2013 at 8:16 — andreih
– andreih, Commented Jun 5, 2013 at 8:16

PSR · Accepted Answer · 2013-06-05 08:16:22Z

2

If you use if the block will execute only once.If you use while the block will execute until the condition false

use while instead of if

while(rs.next()) {
        int id = rs.getInt("id");
        String str1 = rs.getString("Name");
        String str2 = rs.getString("City");
System.out.format("%s, %s, %s\n", id, str1, str2);  
}


rs.next()

will return false when all the records are completed

answered Jun 5, 2013 at 8:16

PSR

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1 Comment

Reporter Over a year ago

We don't know it. The main mistake from the OP is he didn't ilterate through the resultset.

MadProgrammer · Accepted Answer · 2013-06-05 08:16:40Z

0

Change your if to a while...

while(rs.next()) {
    int id = rs.getInt("id");
    String str1 = rs.getString("Name");
    String str2 = rs.getString("City");
    System.out.format("%s, %s, %s\n", id, str1, str2);      
}

answered Jun 5, 2013 at 8:16

MadProgrammer

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Comments

m0skit0 · Accepted Answer · 2013-06-05 08:17:35Z

0

Replace if(rs.next()) by while(rs.next()).

if(rs.next()) means "if we have one result, move to it and do the following"

while(rs.next()) means "while we still have results, move to the next one and do the following".

answered Jun 5, 2013 at 8:17

m0skit0

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Comments

BobMcGee · Accepted Answer · 2013-06-05 08:19:38Z

0

You want to change your if (rs.next()) { To be a while(rs.next()) {

You're only iterating through one row as it is, that will iterate through all of them.

As a best practice, don't make the contents of the while(...) loop too fancy. You want to minimize the per-row processing while iterating, so the connection doesn't stay open too long. Many people just read rows into a List, or print them out (like you're doing).

answered Jun 5, 2013 at 8:19

BobMcGee

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